Conventional state of the art propulsion systems for large civil aircraft typically include one or more gas turbine engines placed under the wings of the aircraft. However, some studies have indicated that so-called distributed propulsion, which involves having numerous smaller propulsion units preferentially arranged around an aircraft, may provide some significant benefits in terms of noise reduction and fuel efficiency when compared with the current state of the art technology.
One option for a distributed propulsion system is to have numerous electrically powered fan units located around the aircraft. However, early studies by the applicant have indicated that novel electrical technology will be required to implement such a distributed electrical system.
One such technology is the creation of a superconducting system to provide the electrical power to the fan units so as to try and reduce the weight of the electrical system.
The concept of using a superconductor for providing electrical power is well known. A superconductor conducts electricity without loss, that is, with zero electrical resistance. In order to be superconducting, current state of the art superconductor materials must be maintained below a critical temperature, current density and magnetic field. If any of the critical limits are exceeded then the superconductor is said to “quench”, at which point it reverts to its “normal” electrical (and magnetic) properties.
One problem presented by the use of superconducting technology in an aircraft arises from weight and the fact that there will likely be a requirement for some redundancy in any system to accommodate a fault.
The present invention seeks to provide a way to help reduce the overall weight of a superconducting electrical system whilst providing some redundancy in the system.